(Mishnah) (R. Meir): If a person buys from a baker, he may tithe from the hot for the cold and vice-versa, even from many shapes.

(R. Yehuda): It is prohibited (hot for cold etc.), as I could say that yesterday's wheat belonged to one person and today's wheat is from a different person.

R. Shimon prohibits (separating from one shape to another) for Terumas Maaser and permits it for Challah.

(Gemara): Until when does R. Meir permit tithing from one for the other (with no concern that he bought flour from two people etc.)? The students of R. Chiya said in the name of R. Yehoshua ben Levi - everything that he bought from the baker in the same 30 days may be used to tithe one for another.

How is this? If he bought from him at the beginning of 30 days, and again in the middle and again at the end of the 30 days - to separate from the first part for the second part (or from the second for the third or vice versa, we view them as) one group; but to separate from the first for the third, we view them as two groups.

Question: (The Mishnah taught that) R. Shimon prohibits (separating from one shape to another) for Terumas Maaser and permits it for Challah. (This shows that R. Yehuda prohibits it for Challah). Would R. Yehuda prohibit it for Challah? Surely it becomes obligated when it's with him (as he's the one who is kneading it)!

Answer: Rather, it's when the baker borrowed Tamei yeast (sourdough) to make his dough (and might have borrowed it from two different people).

Rebuttal: Even (if he did borrow Tamei yeast from two different people), it's the kneading that now obligates this new dough in Challah?!

Answer: Rather, he borrowed a Tamei loaf to fill his oven (as the bread bakes better when the oven if full; and we are concerned that he borrowed it from an Am HaAretz).

Rebuttal: If that's your concern, why did R. Yehuda only prohibit separating from today's for yesterday's and vice-versa; even today's itself should be a problem, because he may have borrowed to fill his oven?!

Answer: Rather, it's like R. Yochanan (in the sugya earlier in the 2nd Perek - see Zevachim daf 93(d), where the Gemara raised a seeming contradiction between the Mishnah there and our Mishnah - in that Mishnah, the Chachamim obligated the baker to tithe and here they obligated the buyer. R. Yochanan answered that) in the Mishnah there, the baker produced it in a state of Taharah; but here, it is in a state of Tumah. (Yesterday, he made his dough in Tumah without separating Challah. So today, when he separates in Taharah, he is separating from that which is exempt for that which his obligated.) (Note: This entry and the coming entries follows the explanation and text of the Maharah MiFulda, who also removed the phrase 'rather it is like R. Elazar...' from the text of this entry, as indicated.)

(R. Yudan father of R. Matanya): Both yesterday and today, it was in Tumah, and it became Tevel in his possession, but he couldn't separate and in fact, in such a case, even R. Yehuda allows separating from one for the other, as the Baraisa teaches...

(Baraisa): R. Yehuda and R. Shimon prohibit Terumas Maaser and permit Challah.

Question: If they both prohibit Terumas Maaser and permit Challah, what's the difference between them?

Answer: According to R. Yehuda - he may not separate from today's produce for yesterday's, or vice-versa; and they do not disagree over Chalah, only over Terumas Maaser - R. Yehuda says that he may tithe from the same day's produce, even from one oven (i.e. shape) to another. According to R. Shimon, he may not separate even from one oven to another (lest the seller bought wheat from two different people).